Multiple stage blower



March 30, 1965 R. H. FREEVOL 3,175,756

MULTIPLE STAGE BLOWER Filed April 17, 1963 3 Sheets-Sheet 1 FIG. 2

INVENTOR. RALPH H. FREEVOL BY 7; 4% v-&

ATTORNEYS March 30, 1965 Filed April 17, 1963 R. H. FREEVOL 3,175,756

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ATTORNEYS March 30, 1965 FREEVOL 3,175,756

MULTIPLE STAGE BLOWER Filed April 17, 1963 3 Sheets-Sheet 3 INVENTOR.

RALPH H. FREEVOL BY 7% MQ ATTORNEYS United States Patent 3,175,756 MULTIPLE STAGE BLQWER Ralph H. Freevol, Niles, Mich, assignor to Garden (Zity Fan and Blower Qompauy, Niles, Mich, a corporation of Illinois Filed Apr. 1'7, 1%3, Ser. No. 273,757 3 Claims. (El. 230--13b) The present invention relates to blowers and more particularly to a multiple stage pressure blower or fan.

In practice, the ability of a blower'to produce a given pressure is closely related to tip speed of the blower rotor, and, since the stress in a given rotor increases as the square of the tip speed, the development of high pressures necessarily requires a construction and materials having the ability to withstand high stresses. A number of materials are available to withstand the stresses at normal temperatures in producing high pressures; however, as high temperature operating conditions, such as for example in the range of 800 degrees to 1,000 degrees Fahrenheit and above, are reached, the strength of most of the readily available materials and those normally used in the conventional or standard blower and fan c011- struction is greatly reduced and rendered unsatisfactory unless a special and often expensive blower or fan construction is used. Various eiforts have been made in the past to obtain the required pressures at the elevated temperatures, but the resultant units have been relatively large, complicated and expensive or otherwise unsuited for general industrial and commercial application. It is therefore one of the principal objects of the present invention to provide a compact and efficient blower which is capable of developing and delivering gases at high pressures and under high temperature conditions without developing any excessive stresses in the blower structure, and which can be constructed from standard, readily available materials.

Another object of the invention is to provide a multiple stage blower of the centrifugal type in which a single rotor is used for all stages and in which the basic single stage blower construction of this type is maintained.

Still another object of the invention is to provide a multiple stage blower of the aforesaid type in which the intake of all stages is in the axial direction and the outlet of all stages is in the radial direction, and in which all stages are enclosed in a single housing with a single rotor without any appreciable flowback occurring between the stages and without any excess stresses being placed on the rotor tip or on the diffusers of any one of the three stages.

A further object is to provide a blower of the aforesaid type which can be easily and economically fabricated using standard equipment and readily available materials, and which can be operated over long periods of time at elevated temperatures with only occasional servicing.

Another object of the present invention is to provide a multiple stage fan or blower of the centrifugal type suitable for high temperature use in which each stage will individually produce a fraction of the required overall pressure with a single blower and without the use of packing glands or special sealing being required between the various stages along the single rotor.

Additional objects and advantages of the invention will become apparent from the following description and accompanying drawings, wherein:

FIGURE 1 is a side elevational view of the present multiple stage pressure blower or fan showing the air inlet passage at the center and the air outlet passage at the periphery thereof;

FIGURE 2 is a side elevational view of the fan or blower shown in FIGURE 1;

FIGURE 3 is a vertical cross sectional view of the blower shown in FIGURES 1 and 2, the section being taken on line 33 of FIGURE 1;

FIGURE 4 is a vertical cross sectional view of the blower shown in the preceding figures, the section being taken on line 4-4 of FIGURE 3, through the first stage of the multiple stage blower;

FIGURE 5 is a vertical cross sectional view of the blower shown in the preceding figures, the section being taken on line 5-5 of FIGURE 3, through the second stage of the multiple stage blower; and

FIGURE 6 is a vertical cross sectional view of the blower shown in the preceding figures, the section being taken on line 66 of FIGURE 3, through the third stage of the multiple stage blower.

Referring more specifically to the drawings, numeral 10 designates the present multiple stage pressure blower or fan having a generally cylindrically-shaped housing 12 with an inlet conduit or passage 14 at the center thereof and an outlet conduit or passage 16 at the periphery thereof. The inlet and outlet conduits may be connected to other conduits leading, respectively, from a source of air or other gases or to remote plates of discharge. In certain installations, either the inlet or the outlet may open directly into the space from which the air or gases are drawn or into the space in which the air or gases are discharged. A suitable base, bracket or fixture is normally provided on the housing for supporting the blower in various operating positions, depending upon the particular installation. The housing may be supported on an individual base or on the bearing base for the blower drive shaft, or on the base of the motor driving the blower.

The housing is divided into three separate chambers 20, 22 and 24 representing the three stages of the multiple stage blower, by partitions 26 between the first and second stages and partition 28 between the second and third stages. The rear side wall 30 of the housing forms the second wall of the first stage, partitions 26 and 28 form the two walls of the second stage, and partition 28 and a partition 32 form the walls of chamber 24. Partitions 26 and 28 terminate in spaced relation to the center ofthe blower housing to fonm a rotor or wheel chamber 34 in which a rotor or wheel 40 is rotatably mounted. The inlet to rotor chamber 34 consists, in the embodiment illustrated in the drawings, of a conduit 42 projecting outwardly from the center of housing 12 and terminating at the inner edge of rotor 40. If the blower is installed to receive its air directly from the space in which the blower is located, conduit 42 may be dispensed with and the bell mouth portion 44 serves as the inlet to rotor chamber 34.

The rotor 40 constitutes the rotor for all three stages and consists of three series of radially and longitudinally extending blades 50, 52 and 54, blades 50 being supported at one end by a disc-shaped end member 56 forming one end of the rotor and being supported at the other end by a bell-shaped partition 58, the outer peri phery of which is in alignment with partition 26 between chambers 20 and 22. Blades 52 are supported at one end by bell-shaped partition 58 and at the other end by a second bell-shaped partition 60, the latter partition being in alignment at its periphery with partition 28 separating chambers 22 and 24. Blades 54 are supported at one end by bell-shaped partition 60 and at the other end by ring 62 forming the intake end of rotor 40. The opening in the center of ring 62 forms the air intake for the rotor and receives the inner end of conduit 42 which discharges the inflowing air into the left-hand side of rotor 40 and bell-shaped partition 58. The blades of each series may be of any suitable design, either the forward, backward or straight radial type, and the blades of one series may be diiierent from the blades of the other series, both as to blade design and number. Partition 58 extends radially inwardly from the periphery of the wheel and curves outwardly toward the fan inlet with a sweeping, substantially uniform radius dividing the wheel into sections 64 and 66, the former being connected to the fan inlet and the latter being connected with chamber 22, as will be more fully described hereinafter. Partition 60 likewise extends inwardly from the periphery of the rotor and curves outwardly toward the fan inlet in spaced relation to the inner end of partition 58, dividing the rotor into sections 66 and 68. While sections 64, 66 and 68 are shown of equal size, i.e. equal peripheral areas of the rotor, the size may be varied from one section to another to obtain various operating results.

At the inner end of the rotor is provided a cone-shaped deflector 70 which serves both to direct the inwardly flowing air radially outwardly through section 34 to chamber 20 and to reinforce the wheel on hub 72. The rotor is rotated by shaft 74 supported by suitable bearings (not shown) on a bearing base and in turn is connected to hub 72 of the rotor. The rotor is driven through shaft 74 by a motor (not shown) connected either by a direct coupling to the shaft or by a belt drive of well known construction and operation.

Chamber 20 of stage one of the multiple stage blower is connected to stage two by an annular conduit 80 extending from the chamber along the periphery of the housing to the inlet of rotor section 52. The conduit extends completely around the periphery of the housing, with the exception of the portion provided therethrough for blower discharge conduit 16, and tapers slightly from its inlet at chamber 20 to its outlet at the inlet of section 52 of the rotor. Chamber 22 of stage two is connected by a conduit 82 extending from the outlet of the chamber along the inner periphery of conduit 80 to the inlet of section 54 of rotor 40, this conduit likewise being tapered throughout its length from its inlet at chamber 22 to its outlet at the rotor. The air discharged from the third stage by section 54 of the rotor passes through a scroll 86 to outlet 16, from which it is delivered to the point of discharge. Chambers 20 and 22 of stages one and two, respectively, are provided with a plurality of blades 88 and 90, respectively, forming diffusers for even distribution and how of the air from the respective rotor sections. The blades 88 and 9d are secured rigidly to the respective walls of chambers 20 and 22.

In the operation of the present multiple stage blower, as rotor 40 is rotated by the motor through shaft 74, air is drawn in through conduit 42 into section 64 of the rotor from which it is discharged under high velocity into chamber 20. Since the chamber is of substantially greater volume than section 64 of the rotor, the velocity is converted to pressure and the air is conveyed through conduit 80 to the inlet of section 66 where it is again pressurized and discharged into chamber 22. The air, on being discharged from section 66 of the rotor, passes into the larger capacity chamber 22 where the air velocity is again converted to pressure and the air is then carried through conduit 82 to the inlet of section 68 from which it is discharged into scroll 86 and thence to outlet passage 16 under high velocity and pressure. Since, in the first two stages, the increased pressure is converted to a relatively low velocity, the stress normally encountered for such pressures is substantially lower and well within the range of the normal capacity of the standard material used in blower and fan construction.

While three stages are illustrated in the present multiple stage blower, either two stages or four, and possibly more, may be used in certain installations. Only one embodiment of the present invention has been described herein; however, various changes and modifications may be made without departing from the scope of the in vention.

I claim:

1. A three stage blower comprising peripheral and side walls forming a housing of generally cylindrical shape with a rotor chamber at the center, three radially positioned partitions in said housing and axially spaced from the side walls of said housing and from each other to form first, second and third chambers, a rotor in said rotor chamber having axially disposed peripheral vanes and two partitions of bell-shaped configuration dividing said rotor into first, second and third sections corresponding to said first, second and third chambers and each of said bell-shaped partitions having a radially extending peripheral portion in alignment with respective ones of said first mentioned partitions, an intake passage at the center of said housing connected with said first rotor section, a first annularly shaped conduit means connecting said first chamber with the second rotor section, said conduit means including a first pair of concentrically spaced wall portions and a second pair of concentrically spaced wall portions radially inwardly of the first pair of concentrically spaced wall portions, the cross-sectional area in a plane normal to the axis of the rotor of the said second pair of concentrically spaced wall portions being substantially less than the crosssectional area in a plane normal to the axis of the rotor of the first pair of concentrically spaced wall portions, a first unitary wall means joining the outermost concentric wall portion to the innermost concentric wall portion by a smooth curved surface, a second unitary wall means joining said other concentric wall portions by a smooth curved surface, the first and second unitary wall means defining therebetween a flow passage continuously converging in cross-sectional area from the first pair of concentrically spaced wall portions to the second pair of concentrically spaced wall portions, a second conduit means surrounded by said first conduit means and having the same general configuration as that of said first conduit means and connecting said second chamber with the third rotor section, an outlet conduit at the periphery of said housing, and a scroll-shaped conduit connecting said third chamber with said outlet conduit.

2. The blower defined in claim 1 wherein a plurality of diffuser blades are disposed in said first and second chambers.

3. The blower defined in claim 1, wherein there is a progressive increase in the size of said chambers from the first to the third chamber.

References Cited by the Examiner UNITED STATES PATENTS 126,639 5/72 Leitel lO3--111 1,119,713 12/14 Moss 230l25 1,138,083 5/15 Carrier 230-134.45 1,309,282 7/19 Frame 103109 1,886,816 12/32 White 103103 3,102,680 9/63 Fogleman et al. 230- FOREIGN PATENTS 345,856 12/21 Germany.

225,640 12/24 Great Britain.

341,640 1/31 Great Britain.

619,374 3/49 Great Britain.

86,765 10/20 Switzerland. 87,263 4/21 Switzerland.

JOSEPH H. BRAN SON, ]R., Primary Examiner. 

1. A THREE STAGE BLOWER COMPRISING PERIPHERIAL AND SIDE WALLS FORMING A HOUSING OF GENERALLY CYLINDERICAL SHAPE WITH A ROTOR CHAMBER AT THE CENTER, THREE RADIALLY POSITIONED PARTITIONS IN SAID HOUSING AND AXIALLY SPACED FROM THE SIDE WALLS OF SAID HOUSING AND FROM EACH OTHER TO FORM FIRST, SECOND AND THIRD CHAMBERS, A ROTOR IN SAID ROTOR CHAMBER HAVING AXIALLY DISPOSED PERIPHERALY VANES AND TWO PARTITIONS OF BELL-SHAPED CONFIGURATION DIVIDING SAID ROTOR INTO FIRST, SAID AND THIRD SECTIONS CORRESPONDING TO SAID FIRST, SECOND AND THIRD CHAMBERS AND EACH OF SAID BELL-SHAPED PARTITIONS HAVING A RADIALLY EXTENDING PERIPHERAL PORTION IN ALIGNMENT WITH RESPECTIVE ONES OF SAID FIRST MENTIONED PARTITIONS, AN INTAKE PASSAGE AT THE CENTER OF SAID HOUSING CONNECTED WITH SAID FIRST ROTOR SECTION, A FIRST ANNULARLY SHAPED CONDUIT MEANS CONNECTING SAID FIRST CHAMBER WITH THE SECOND ROTOR SECTION, SAID CONDUIT MEANS INCLUDING A FIRST PAIR OF CONCENTRICALLY SPACED WALL PORTIONS RADIALLY INWARDLY OF CONCENTRICALLY SPACED WALL PORTIONS RADIALLY INWARDLY OF THE FIRST PAIR OF CONCENTRICALLY SPACED WALL PORTIONS, THE CROSS-SECTIONAL AREA IN A PLANE NORMAL TO THE AXIS OF THE ROTOR OF THE SAID SECOND PAIR OF CONCENTRICALLY SPACED 